Currently, a network such as the Internet is constituted by equipments having a variety of communication resources, and a variety of communications are taken place in such a network. This requires grasping a status of the network such as a delay or an available bandwidth. As such a network measurement technique, an active measurement in which a status in a network is measured by transmitting data (a packet) for measurement to the network is known.
Patent Literature 1 describes a system in which a plurality of measurement packets whose packet size increases or decreases sequentially are transmitted at a predetermined transmission interval, reception intervals of the measurement packets are measured, and the transmission interval of the measurement packet is compared with the reception intervals to calculate an available bandwidth. In this system, an available bandwidth is calculated by using a measurement packet whose packet size is the largest among measurement packets in which the reception interval is equal to the transmission interval.
Patent Literature 2 describes generation of an estimate value of a QoS (Quality of Service) parameter (for example, available bandwidth) by transmitting an ICMP (Internet Control Message Protocol) time stamp request to all routers on an end-to-end path.